Threading die



May 18 19:26. 1,584 ,898

J. A. SMITH THREADING DIE Filed August 11, 1923 INVENTOR. 2&

ATTORNEY- Patented May 18, 1926.,

v JAMESZAQ" SMITHfOFWTNDSGR, 'CONNE'C'IIGUT.

*ITHREADING1DIE.

dfipplidation filed August 11, .*1 923. SeriaI--No. 656,7.66.

. .My invention relates totthe class 'ot-Ldei i'ces -ithat are'eniployed for cutting screw threads, and an ob ect ofrrny inventionamong others,

.isthe production in asrapidzsimple,

*- 5 expensive mannerofma andin- (116 having improved features as to itscharacteristics.

Myiinproved die-andthe nannenoticreat- "ing -itaand inthe-const-ructionand useot which theobjects: herein others,rn ay be-rattained,iacconipanyingadrawings is illustrated'in-the in Which- .-nary-stepsintheimalrin have been taken.

,- Eigurezfzrisia View in the same.

a Figure 3 is g o 'my mp d die 1. .r

s 111g those, -'port1ons which .traveli-ahead When thetool is rintolan dtake hold .ofthe, piece upon which lathread is to be cut, andthus tobegin'lthe f thread cutting operation upon such piece and set out,-aswell-res v I parts located between lthe chip or clearance holes. andextending tow i pered fbEICkV ardly from? cross section thr-ough Iview-similar to Figurewlibut i-illustratingian advanced stepan theoperai crosssection through View sini-ilar to Fig -=n-re1 butillustratinga sti ll-lfurther and-ad- Figure 6 is a View in the same.

, :Fagure'? 1 -15 avanced step in the making oft-he die. I

cross section through :1 V I -erable. I side view of astool devised a.by .me *for. use intcarryang put any invent-ion,

\ of the itool.

Figure 8 is an end View of saidtool.

'IeW .of improved -v die in its completed. tforrn.

through the sarne.

Figure l 11 a enlarged, lthrough plane denoted by GFi'gure 410 .is -.aview in cross section =il lustrate-the improved characteristics ot thedie.

In-the making -.of Idies rfor cutting-screw threads {past to lpiecerofit hasI-been common practiceuin the le in :the center of a -.-1naterialto :constitute t die, Which hole is then tapped. Then a'nurnberiof chip=or clearance holes are -i these lbei-ng located 1 thread cuttingrbetween": the center irnade in the piece,

material ance holes to be eventuallygcntaway. g

In :order to cause .the cutting ithreads of 'the center and I threade dholezto readily cut td'leaditdnto the diei thevzthroat of the cenxterand thread cutting hole; issprovided with what "may .be aptly termed. a'lead 1' that takes lthe .fornr of. a bevel that .xexten'ds in thedirection 7. of depth of 'the .hole on the cutting. portions or-lands,,z;which .arelthose ar'dsthe center'of :Ithel'die and thesebeveled parts arealso tathe front to'therear edges or such lands,saidfront edges beoperating to cut a thread.

t In:for1n1ng this "'tlezid it L-h'as been; custo-niary heretofore toemploy -az'file, arid in some instances IHL'lllHgutOOl. has been. used,

Ybutfei'ther. operation takes. much time and reman :lexpenslveope-ration,

.. intheiformation ensure I this View also illustrating the manner: ofuse A g V. efficient manner and lwlthout requir ng 3 an quires great\care Hand considerable skillto aVOidJmu-tilatiQn of threads other thanthose :upon which" the work. is being done. lOonse qnently the"formation for suchllea'da-has been original expense of the die" has beenconsid- .By employing vraydin proved construction ram enabledfltoproduce-such diein ia particularlyrapid and .dncing'the cost of,producing the die, and'at the=same time-I am enabled to provide, afdiethat isnmore durable than lthoseihavifngithe- Qlea-d ,;produced by s acutting operation as her ei nbefore .r'eferre'dfto.

I V 'lIn =constructing my lmprovedd1e I first take a piece ofniaterial10, oft-the. desired .form, as roundor rectangular in cross section, anddrill a lcen- ,liter or thread ciitting'hole '11 therein; which hole iseventuallybeveled at its. mouth or V at equaldistances apart and at such-.distances ifrorn the center and *lioleas toenablelthe hole andthe'ehip orflclea'r- 1 man the same as-1 manzner of forming I havingsuch lead is,-

muzzie to. produce 5 the iflead', as herein'betfore described withrespect' to;;-prior.dies," the form .or shape of .thisi-lead beingsubstanthat. of,prio'r dies. JThe this llead and the die however,aniinpoi'tant feature or any present invention, which" c'f ntemplatesthe formation of such 'lea'd by compressing or condensing the .metal fatthe month of the thread cutting hole .11 and conseqnently atthe enteringends; of thela'n' ds '13, which compressing or condensing of: the metalmay be (effected i in any desired Trianan'd; Tthereforathenor,preferably by swaging. In the preferred manner of effecting thiscompressing or swaging operation, I employ a swaging or lead formingtool 12, properly shaped, and which is forced into the mouth of the holeto mold or swage the material of the lands about the mouth of the holeto the desired shape to produce the lead. This operation of forming thelead may take place at different stages in making the die, but I preferto form, such lead as one of the preliminary steps in the operation. Itwill be found, however, that such lead may be formed after the centerand thread cutting hole has been threaded, but by forming it before suchthreading, distortion of the threads is avoided and a subsequentoperation to correct the distorted thread is not required.

In forming the lead of the die as herein contemplated I preferablyconstruct said tool 12 with its working end properly shaped to producethe lead. This end of the tool is beveled to a degree to produce abeveled edge 14L of proper shape at the mouth of the thread cutting hole11 and on the lands 13 should they exist at this time, and in order toproperly shape the end of each land as to taper I provide as manyswaging faces 15 on the tapered end of the tool as there are lands inthe die to be made. These faces are tapered from a ridge 16 at one edgeof each face to the bottom of a groove 17 that terminates at theperpendicular edge of the adjacent face, and as shown in Figure 7 of thedrawings. In other words, each of the faces 15 of the tool is of a shapeto correspond both in bevel and taper to the ends of the lands in themouth of the hole in the die to be made, and when the tool is forcedinto the hole 11 those portions of the piece that will eventuallycomprise the ends of the lands 13, if the swaging be done in apreliminary step in the operation, or those portions constituting theends of such lands, if the swaging be done after the formation of thethreads, will be properly formed both as to tappr and bevel to produce amost etiicient leac.

When the swaging takes place as a preliminary step in the operation Ipreferably first form the center hole 11 and then the chip or clearanceholes 18 are made. The tool 12 is then employed to produce the lead, asshown in Figures 3 and at of the drawing, the thread 19 may then beproduced, as illustrated in Figures 5 and 6 of the drawing, and theentrances 20 to the chip holes 18 may then be cut in any desired mannerto produce the completed die as illustrated in *igure 9.

IVhen the lead is produced as a more advanced step in the operation, thework of the swaging tool is effected after the forma tion of thethreads, and preferably after the chip or clearance holes 18 are made.It will,

therefore, be obvious that this swaging operation may take place atvarious stages in the construction of the die and I do not, therefore,limit my invention to the swaging as taking place at any special step insuch construction.

A die produced as hereinbefore described has the metal of a workingportion, that is the lead on the ends of the lands 13, compressed andcondensed, with a consequent beneficial result of a cutting edge havingincreased durability over a die in which the metal is not condensed.

The bevels forming the leads on dies of various sizes are substantiallythe same, and it will, therefore, be obvious that a single swaging toolmay be employed to bevel dies of .a wide variety of sizes. A dieproduced in accordance with my invention will possess a maximum degreeof uniformity as to the several cutting portions thereof, suchuniformity greatly exceeding that possessed by a die in which theseveral cutting operations are separately performed by hand work.

In accordance with the provisions of the patent statutes I havedescribed the principles of operation of my invention, together with thedevice which I now consider to represent the best embodiment thereof;but I desire to have it understood that the device shown in onlyillustrative, and that the invention may be carried out by other meansand applied to uses other than those above set out.

I claim 1. A threading die having a thread cutting hole comprising alead, with the metal comprised in such lea-d more dense than the metalcomprised in parts of the thread cutting hole, thereby toughening acutting part of the die.

2. A threading die having a thread cutting hole with a beveled mouthforming a lead, with the metal comprised in such lead more dense thanthe metal comprised in other parts of the hole, thereby toughening thecutting edge of the thread cutting hole in the die.

3. The process of forming a threading die that consists in making athread cutting hole in a piece of material, and as a step in the processforcing the beveled end of a lead forming tool having backwardly taperedfaces into the mouth of the thread cutting hole to compress the metaland form a lead.

a. The process of forming a threading die that consists in making athread cutting hole in a piece of material, and as a step in the processcompressing the metal at the mouth of said hole to form a lead, andafterwards threading said hole.

5. The process of forming a threading die that consists in making athread cutting hole in a piece of material, beveling the edge of saidhole" to form a lead, cutting chip or clearance holes before thebeveling operation which holes are opened into the threadcutting hole,and afterwards threading said thread cutting hole.

6. The process of forming a threading die that consists in making athread cutting hole in a piece of material, forming clearance holes insaid material with landportions therebetween, and as a step in theprocess forcing the beveled end of a lead forming tool having swagingfaces larger in diameter than said thread cutting hole into the mouth ofsaid thread cutting hole and against the lands to compress the metalthereof to form a lead, and also, as a step in 1the process, threadingsaid thread cutting 7. The process of forming a threading die thatconsists in making a thread cutting hole in a piece of material, formingclearance holes in said material with land portions therebetween, and asa step in the process forcing the backwar-dly tapered annularly disposedswaging faces on the beveled end of a lead forming tool, said facescorresponding in number and location to said lands, into the mouth ofsaid thread-cutting hole and against said lands to compress the metalthereof to form the lead, and also, as a step in the process, threadingsaid thread-cutting hole.

JAMES A. SMITH.

